1. Field of the Invention
The present invention relates to door locks, and in particular to operating mechanisms for door latch bolts which provide positive reliable operation.
2. Prior Art
In the prior art various patents have advanced different types of door locks and latches. A pivoting latch dog for a door lock is shown in U.S. Pat. No. 307,281. However, the door lock does not provide means for preventing forcible entry nor is it electrically operated. The patent to Wells, U.S. Pat. No. 1,184,498 shows a toggle linkage actuated pivoting bolt, but the mechanism illustrated and described does not suit itself well for security necessary at the present time, nor does the linkage suggest any way that would permit operation through electrically actuated means. Another type of pivoting door bolt or latch dog is shown in U.S. Pat. No. 1,435,971. The lock is manually operated by a pivoting lever, in this particular instance, and it appears to applicant that the door must be pushed, after the lock is released, in order for the door to open. In other words, the door is not positively opened by actuation of the lock dog.
A type of silent door latch is shown in U.S. Pat. No. 2,848,263, issued to R. G. Miller, and a linkage is provided to exert a spring pressure against the door in a closed position to eliminate rattles and the like in this particular patent. Similarly, U. S. Pat. No. 3,667,793 shows a rotatable latch dog or cam that is operated through a sliding member, and which rotates to hold the door as the door is closed.
The patent to Leonard et al., U.S. Pat. No. 1,269,467 shows a pivoting latch for a refrigerator door that has a spring load tending to impel the door to open position when the latch is released.
Other patents that include linkage for operation of locks include the Pearce U.S. Pat. No. 2,189,992 showing an automobile door lock; U.S. Pat. No. 1,670,793 to Schrader which shows a snap closure fastener having a manually actuable handle; the U.S. Pat. to Miller No. 1,937,978 also showing a latch for a refrigerator door that has a spring loaded, manually actuated linkage; U.S. Pat. No. 2,016,519 to Schmidt which shows a door latch that also is spring loaded and manually operated; U.S. Pat. No. 2,867,465 issued to Van Noord showing a latch control mechanism that insures that a door such as a refrigerator door is drawn tightly shut when it is closed; U.S. Pat. No. 2,833,578 issued to Burke, shows another type of refrigerator door latch using a snap action closure latch dog; and U.S. Pat. No. 2,650,846 to Allen which shows a latch for a vehicle door using a complex manually operated linkage.